Energy

Energy

A geyser, caused by geothermal energyA geyser, caused by geothermal energy Energy is the ability to make things happen, cause changes and carry out work. Any change anywhere in the Universe, from a tiny meteorite hitting a planet to an exploding star, means that energy is at work. In daily life, energy is all around us in many different forms. Light and sound energy travel through the air as waves. Heat is a form known as thermal energy. Geothermal energy from hot rocks deep in the Earth causes geysers, jets of hot water and steam. Movement or motion is another form of energy; it is called kinetic energy. Other forms include electricity, chemical energy and nuclear energy.

 
Different forms of energyDifferent forms of energy
Potential energy is stored in the bow's bent arms.Potential energy is stored in the bow's bent arms.Click to play video

Potential energy

Objects even have energy because of their place or position. This is called potential energy. A boulder on a hilltop has potential energy because gravity tries to pull it down. As the boulder begins to roll its potential energy changes into kinetic energy.
 

Energy being converted from one form to another.Energy being converted from one form to another.

Converting energy

Energy can cause changes and it can change itself. It can convert between one form and another. Light energy from the Sun enables food crops to grow. The chemical energy in the food is changed to kinetic energy when you eat it. The kinetic energy changes to sound energy when you move around. Electrical energy, itself produced by chemical, kinetic, nuclear or heat energy, can be changed into many other forms of energy, such as light from a light bulb, heat from a kettle or sound from a CD player.
 

This aircraft's fuel is stored chemical energy.This aircraft's fuel is stored chemical energy.

Chemical energy

Matter contains chemical energy, in the links or bonds between atoms. The bonds need energy to form and they release this energy when they are broken. We make use of chemical energy in fuels such as petrol. The bonds break as the fuel burns and releases heat, driving internal combustion, jet and rocket engines.



The human body needs energy to drive its life processes like heartbeat, breathing and movement. The energy is present in chemical form as the nutrients in our food. We digest the food to obtain the energy and store it as body starches and sugars.
 

Energy in different forms is all around us.Energy in different forms is all around us.

Conserving energy

Energy can be changed or converted from one form to another. But it is never destroyed or created, lost or gained. It is conserved—the amount stays the same. At the end of a process or event, the total amount of energy is the same as at the beginning. For example, the chemical energy in a car’s petrol is converted into the same amount of energy as the car’s motion, heat and sound. The principle of energy conservation means the total amount of energy in the Universe is always the same.


Consultant:
 Dave Hawksett

See also in Science

See also in Space

See also in Science

See also in Geography

Dark energy is a kind of energy that we can neither see nor feel. It is found in space, and thought to be responsible for accelerating the expansion of the Universe. Dark energy accounts for 73% of all the energy in the Universe.

Matter may be destroyed and converted to energy, but mass can never be destroyed.

Plants use the light energy from sunlight during photosynthesis—their way of making food by combining carbon dioxide and water and converting it to glucose.

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